Not another LLM eval platform.
A runtime layer built for MCP.
Langfuse and LangWatch are excellent tools for LLM evaluation and prompt quality. LangSight solves a different problem: monitoring and securing the tools your agents call at runtime — the MCP servers, HTTP APIs, and functions that break silently without anyone noticing.
LangSight
MCP-nativeRuntime observability for AI agent toolchains. Purpose-built for MCP server monitoring, security scanning, schema drift detection, and tool call tracing.
Langfuse
LLM eval & tracingStrong platform for LLM prompt engineering, evals, and cost tracking. Not designed for MCP server health or security — complementary to LangSight.
LangWatch
Quality & guardrailsFocuses on LLM output quality, guardrails, and safety evaluations. Does not cover MCP infrastructure health, CVE scanning, or tool-level security.
Feature comparison
What each platform covers
Green rows are unique to LangSight — capabilities no other platform offers today.
| Feature | LangSight | Langfuse | LangWatch |
|---|---|---|---|
| MCP server health monitoringLangSight is the only platform with native MCP health checks. | Yes | — | — |
| MCP security scanning (CVE + OWASP)CVE detection and 5 of 10 OWASP MCP checks, built-in. | Yes | — | — |
| Tool poisoning detectionInjection, unicode, and base64-encoded payload detection. | Yes | — | — |
| Schema drift detectionAlerts when a tool's schema changes unexpectedly between scans. | Yes | — | — |
| Agent tool call tracing | Yes | Yes | Yes |
| LLM input / output capture | Yes | Yes | Yes |
| Multi-agent call tree | Yes | Partial | Partial |
| Cost attribution per tool call | Yes | Yes | Partial |
| Anomaly detection | Yes | — | Partial |
| SLO tracking | Yes | — | Partial |
| CI/CD security gate (--ci flag) | Yes | — | — |
| Self-hosted (free forever) | Yes | Yes | Yes |
| Data leaves your network | Never | Optional | Optional |
| License | Apache 2.0 | MIT / ELv2 | Apache 2.0 |
| Primary focus | MCP runtime + security | LLM evals + tracing | LLM quality + guardrails |
Comparison based on publicly available documentation as of March 2026. Features may change — check each project's docs for the latest.
LangSight + Langfuse work great together.
Use Langfuse for prompt evaluation and LLM quality. Use LangSight for the runtime layer — MCP health, security, and tool call tracing. They solve different problems at different layers of the stack. No overlap, no conflict.